JEDEC faster than XMP

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IAnarchyReignsI

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Aug 9, 2013
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I was looking at CPUZ on my desktop and was looking at the timings for the ram.
I have a set of Crucial Ballistix Sport Low Profile 2x4gb 1600mhz
I know the reviews on newegg have it at a 2/5 stars but my set has been working perfectly (with intel i5 4670k with stock clock for now) since I got the computer built.

I've got the ram in slots 1 and 3

This is the timing table that I get from CPUZ (I don't have any account for image hosting)

JEDEC6 JEDEC7 XMP1600 XMP1600
Frequency: 888MHz 977MHz 800MHz 800MHz
Latency: 10 11 9 9
RAS-CAS: 10 11 9 9
RAS Prec. 10 11 9 9
tRAS: 27 30 24 24
Voltage: 1.28 1.28 1.35 1.5


Looking at these timings, does that mean that I can be running this memory at 1954MHz or 1866MHz and still be within JEDEC Spec?
I would just need to change all the bios stuff to match the values on the JEDEC6 or 7 setup.

Is there any downside to this?
 
Solution
Tradesman1
Maybe, maybe not, It's never a good idea to mix DRAM, even of the same exact model. There's no guarantee the sticks will play together, which is why DRAM comes in a wide variety of numer of sticks and total DRAM, also each package has been programmed with XMP settings for that particular package, i.e. a set of 2 sticks model XYZ may show the same exact freq, base timings and voltage as a 4 stick package of XYZ, but they will require different advanced timings, again, i.e. the 2 stick set may require and advanced timing of 216 for the tRFC while 4 sticks will need a tRFC of 278....DDR and DDR2 was rather easy to mix sticks, but DDR3, with it's much tighter tolerances isn't near as easy, especially in freqs 1600 and up, which is why there...
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IAnarchyReignsI

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Aug 9, 2013
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The table got messed up

Profile, Frequency, Latency, RAS-CAS, RAS Pre., tRAS, tRC, Voltage
JEDEC6-888MHz-10-10-10-27-42-1.28
JEDEC7-954MHz-11-11-11-30-46-1.28
XMP1600-800MHz-9-9-9-24-37-1.35
XMP1600-800MHz-9-9-9-24-37-1.5
 
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Tradesman1

Tradesman1

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Jun 5, 2013
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Those basically are suggesting some extremely loose timings if you wanted to to try and OC the sticks - rather weird ones at that, normally if you were to OC it would typically be to 1866 and you'd start at 10-10-10-27 w/ 1.55 - what these numbers show don't make any real sense as the 1600/9 will offer better performance than either the suggested 1776/10 or the 1908/11 indicated
 
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noidea_77

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Jul 28, 2012
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Right, but the JEDEC specs are for very low 1.28v

 
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Tradesman1

Tradesman1

Legenda in Aeternum
Jun 5, 2013
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As far as pure performance goes 1600/9 roughly equates to 1866/10 other than the 1866/10 has just a slight advantage in that it has wider bandwidth, you'd lose that with the freq at 1776, and you don't gain enough freq wise at 1908 to overcome the even slower CL11 at that point - so the native 1600/9 would provide the best overall performance
 
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IAnarchyReignsI

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in order to maintain consistent performance I would want to get the best performance I would want the ram timings to be as low as possible as well as the frequency be as high as possible

So if I see a 2x4gb kit with 1600MHz 10-10-10-27 It would be slower despite the frequency being the same.

One more semi related question,
This is the specific set I have:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820148662
say I want to get up to 16gb would this set play well with these since the timings are the same for what I can tell as well as the voltage?
http://www.newegg.com/Product/Product.aspx?Item=N82E16820313345
http://www.newegg.com/Product/Product.aspx?Item=N82E16820211768

But this one would be slower because of the latency of 10
http://www.newegg.com/Product/Product.aspx?Item=N82E16820220806

I am operating on the assumption the ram can only act as fast as the slowest stick. Is this correct?
 
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Tradesman1

Tradesman1

Legenda in Aeternum
Jun 5, 2013
67,883
40
126,960
Maybe, maybe not, It's never a good idea to mix DRAM, even of the same exact model. There's no guarantee the sticks will play together, which is why DRAM comes in a wide variety of numer of sticks and total DRAM, also each package has been programmed with XMP settings for that particular package, i.e. a set of 2 sticks model XYZ may show the same exact freq, base timings and voltage as a 4 stick package of XYZ, but they will require different advanced timings, again, i.e. the 2 stick set may require and advanced timing of 216 for the tRFC while 4 sticks will need a tRFC of 278....DDR and DDR2 was rather easy to mix sticks, but DDR3, with it's much tighter tolerances isn't near as easy, especially in freqs 1600 and up, which is why there are so many threads from folks, who've listened to the 'experts' that say 'sure just add another stick or 2', that are complaining the DRAM they added isn't working, o their system won't even boot, etc
 
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